Method of Monitoring Cells in Wireless Communication Systems

ABSTRACT

A wireless communication network automatically tests itself for sleeping cells. This is done by designing the base stations to regularly act as a terminal, contact its neighboring base stations and as a mobile perform a set of typical traffic cases. From the outcome of the traffic cases the probing base station detects neighboring base stations that cannot carry traffic. The information about sleeping cells is subsequently communicated from the base station to the operation and maintenance system.

TECHNICAL FIELD

The present invention relates in general to radio communications and inparticular to a method and a device for monitoring cells in wirelesscommunication systems.

BACKGROUND

Wireless communication networks are well known and increasing inpopularity. Mobile terminals, such as cell phones, wirelesslycommunicate through base stations or node B's in WCDMA that areassociated with different cells or sectors in a geographic region, forexample. With the increasing popularity and increased competition inwireless communications, system reliability and availability to the enduser, is increasingly important.

The costs for operating radio networks are an increasing part of theoperator's expenditure (OPEX). The OPEX is expected to further increaseas the number of base stations, their geographical distribution across awide area and the nature of wireless links require complex andsophisticated fault detection and recovery schemes. Fault detection is arequired element of an approach to maintaining high reliability andavailability. The challenge is to keep capital expenses under controlwhile maintaining reliability and availability.

One significant scenario that can affect the reliability andavailability of a wireless system is when one of the cells is a“sleeping cell”. A sleeping cell as that term is used in thisdescription is a faulty cell that has not generated an alarm or in anyother way indicated a problem but still is not capable of carryingtraffic. This can be caused e.g. by faulty configuration, faulty radiocircuits or other critical hardware, memory or other resource leakage.One particular example could be that the configuration of broadcastinformation is corrupt so that mobile stations cannot read the systeminformation required to access the radio cell. The impact of a sleepingcell is that mobile terminals in the corresponding coverage area cannotbe served as the service disappears in a sleeping cell.

Detecting a sleeping cell in the existing technology is performed bymanually monitoring the traffic patterns in a network. Cells thatnormally carry non-zero traffic volumes but where the traffic volume isseen to be zero for some time are listed as candidates and the networkoperator then visits the cells and actively checks if the site isworking or not. The main problem with this approach is that all cellsduring times have no traffic due to low subscriber activity. Hence it isdifficult to deduce if a time period of no traffic in a cell is causedby the cell being a sleeping cell or caused by the fact that nosubscriber has tried to access the system. This causes problems inparticular in cells with only moderate amount of daily traffic where afull day of zero traffic could but need not indicate a problem.Detecting a sleeping cell is more complex still when one considers thatthe amount of traffic varies at different times of the day duringdifferent seasons of the year.

A critical component in the method above is thus to determine just howlong time of no traffic indicated should qualify a cell as a candidatesleeping cell. A too long time, like a week, would mean that trulysleeping cells would be identified and fixed at the earliest one weekafter the problem of the sleeping cell first occurred. Thus to set along time before to react can lead to lengthy periods of serviceabsence.

In contrast, a too short time, like an hour, would lead to manyperfectly well-working cells (which due to subscriber inactivity haveserved no end-user during the hour) would be put on the list fortime-consuming site visits. Hence a too short time leads to unnecessaryand costly site visits to well-working cell. This leads to unnecessaryand costly site visits to cells identified as faulty but where the mainreason of no traffic is that no user tried to be connected for one day.

Traditionally, operator takes action only when zero-traffic persists forquite some time, i.e. one to three days. This to avoid site visits dueto false alarms. However cells that take traffic only few days per week,but which are still important due to service coverage consideration arevirtually impossible to detect as sleeping cells.

Consequently, one serious drawback with the method described above is atrade off between costly site visits and the time to react.

Hence there exist a need for a method and arrangements for automaticallydetecting sleeping cells and that at the same time are efficient interms of fast detection and economical in terms of less site visits dueto false alarms.

SUMMARY

A general problem with the wireless communication networks is thatdetecting a sleeping cell is difficult and costly. The operator has torely on indirect indicators that are not accurate and lead to falsealarms.

A general object of the present invention is to provide improved methodsand arrangements for monitoring and checking sleeping cell candidates.

A further object of the present invention is to provide methods andarrangements giving opportunities for more accurately detecting basestations that can not carry traffic, i.e. sleeping cells.

A further object of the present invention is to provide a methodenabling a first base station to monitor a second base station which issuspected of not being able to carry traffic, i.e. sleeping cellcandidate.

These and other objects are achieved in accordance with the attached setof claims.

A first embodiment of the present invention provides a method forenabling a first base station to monitor a second base station in acellular communications system, wherein the first base station sets up aradio communication channel and monitors the setting up procedure ofsaid communication channel.

Another embodiment of the present invention provides a method forenabling a first base station to monitor a second base station in acellular communications system, wherein the first base station sets up aradio communication channel. The established radio communication channelis used to upload and download data files between the first base stationand a content server through the second base station, wherein the secondbase station monitors the data files transfer.

Yet another embodiment of the present invention provides a first basestation for monitoring a second base station in a cellularcommunications system. Said first base station comprises a radiotransceiver and a controller for setting up a radio communicationchannel with the second base station. Said controller is further adaptedto monitor the setting up procedure.

Yet another embodiment of the present invention provides a first basestation for monitoring a second base station in a cellularcommunications system. Said first base station comprises a radiotransceiver and a controller for setting up a radio communicationchannel with the second base station. Said controller is further adaptedto upload data files to a content server and download data files fromthe content server through the second base station. Said controller isfurther adapted to monitor the data files transfer.

An advantage of the present invention comprises enabling accurate andeconomical detection of sleeping cells. Since the method is not based onindirect indicators such as traffic patterns, the number of false alarmscan be reduced to a minimum. With prior art a period of low trafficwould indicate a cell as “sleeping” with a probability which may be aslow as 50%, depending on the type of cell. In contrast, the presentinvention actively probes the base station so that a fault indication isaccurate to within a fraction of a percent.

Another advantage is that the probing can be done as often as desiredand the time from base station fault occurrence and detection isdramatically reduced. The probing could also be configured to beexecuted after only an hour on no traffic so that sleeping cells aredetected and alarmed to the operator at most sixty minutes after theoccurrence of the problem. This dramatically decreases the service downtime resulting from sleeping cells.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described in more by way ofnon-limiting examples and with reference of the accompanying drawings,in which:

FIG. 1 is a schematic view of a cellular communication system accordingto the invention;

FIG. 2 is a view of a protocol for transmission illustrating uplink anddownlink communication in time domain according to the prior art;

FIG. 3 is a schematic flow diagram according to one aspect of theinvention;

FIG. 4 is a schematic flow diagram according to one aspect of theinvention;

FIG. 5 is a function block diagram of a non-limiting example of a basestation for monitoring a candidate base station according to theinvention;

FIG. 6 is a view of a protocol for transmission illustrating uplink anddownlink communication in time domain according to the invention.

FIG. 7 is a signalling diagram according to one embodiment of theinvention.

FIG. 8 is a signalling diagram according to another embodiment of theinvention.

DETAILS DESCRIPTION

In the following description, for purposes of explanation andnon-limitation, specific details are set forth, such as particularnodes, functional entities, techniques, protocols, standards, etc. inorder to provide an understanding of the described technology. It willbe apparent to one skilled in the art that other embodiments may bepracticed apart from the specific details disclosed below. Thetechnology is described in the context of a Long Term Evolution (LTE) ofUMTS in order to provide an example and a non-limiting context forexplanation. The ideas of the present invention are equally applicableto many types of cellular systems consisting of a plurality of basestations, where accurate and economical detection of sleeping cells isnecessary but difficult to provide.

In other instances, detailed descriptions of well-known methods,devices, techniques, etc. are omitted so as not to obscure thedescription with unnecessary detail. Individual function blocks areshown in the figures. Those skilled in the art will appreciate that thefunctions of those blocks may be implemented using individual hardwarecircuits, using software programs and data in conjunction with asuitably programmed microprocessor or general purpose computer, usingapplications specific integrated circuitry (ASIC), and/or using one ormore digital signal processors (DSPs).

Universal Mobile Telecommunications System (UMTS) is one of thethird-generation (3G) mobile phone technologies. Currently, the mostcommon form uses W-CDMA as the underlying air interface, is standardizedby the 3rd Generation Partnership Project (3GPP), and is the Europeananswer to the ITU IMT-2000 requirements for 3G cellular radio systems.The Long Term Evolution (LTE) of UMTS is under discussion by the 3GPPwhich standardized UMTS. The objective of the LTE work is to develop aframework for the evolution of the 3GPP radio-access technology towardsa high-data-rate, low-latency and packet-optimized radio-accesstechnology. So the focus is on supporting services provided from thepacket switched (PS)-domain.

FIG. 1 illustrates a LTE system 10 sometimes referred to evolved-UTRAN(e-UTRAN). The LTE system includes Base Stations (BS) 14 whichcommunicate together over an X2 interface. The base stations 14 aresometimes referred to as enhanced node B's (eNBs) because of theadditional functionality performed by the base stations as compared toregular UTRAN base stations. The base stations 14 communicate over an S1interface with an evolved packet core (EPC) which includes one or morenodes labeled as mobility management entity (MME)/System ArchitectureEvolution Gateway (SAE-GW) 11 and with a content server 19 via theSAE-GW 11.

The base stations 14 communicate over the radio/air interface with radioMobile Terminals (MT) 16 also referred to as User Equipment (UE). Aplurality of cells or sectors includes base stations that aregeographically distributed in a known manner. The portion of the examplesystem that is illustrated in FIG. 1 includes two cells 17 and 18.

In one example the base stations 14 communicate over an M interfaceillustrating one example of communication interface but could be anyother interface as well, with a monitoring module 12 that monitors theperformance of the system. The monitoring module 12, which is connectedto the operation and Maintenance Center (OMC) 13, includes software,hardware, firmware or a combination of them designed to monitor thesystem for fault conditions. A variety of fault conditions may bedetermined. A sleeping cell is considered as an example of faultconditions in this document, and other fault conditions may be detectedusing an appropriately designed embodiment of this invention.

In another example the monitoring module 12 is maintained independent ofcritical components responsible for cell or network operation, forexample, in the OMC 13 within the operation and maintenance (O&M) systemof the operator. In another example (not shown) the monitoring module 12may be incorporated in the MME/SAE-GW 11. There need not be a singlephysical location for the various components or portion of themonitoring module 12. In one example, each cell 17 and 18 has amonitoring module 12 associated with it that then communicates with acentral unit, for example, when a central unit is used for monitoring ormaking determinations regarding potential fault conditions or actualfault conditions.

Furthermore, the base stations 14 communicate with a content server 19via the SAE-GW 11. The content server 19 is a server that providesapplications like web based applications or other applications to themobile terminals. The content server 19 may be seen as a separate nodeas shown in FIG. 1, or as a unit incorporated in another node likeMME/SAE-GW.

One skilled in the art realizes the infrastructure depicted in FIG. 1may further include other network elements, such as one or more gatewaysand one or more Operations and Maintenance Centers (OMC). FIG. 1 isprovided merely to illustrate the principals of the present inventionand is not intended to be an exclusive depiction of communication system10.

In the standardization work within LTE, Frequency Division Duplex (FDD)mode and Time Division Duplex (TDD) mode are standardized. The idea ofthe invention will be described in the TDD mode of LTE system, but isequally applicable to the FDD mode of LTE system as well.

Referring to FIG. 2, protocol for transmission uplink and downlinkcommunication in time domain is illustrated. In the TDD mode of LTE ispresented, an unpaired frequency band is defined from which both theuplink and downlink channels are selected. A TDD transceiver cantherefore not transmit and receive simultaneously. The uplinkcommunication and downlink communication in the TDD system isalternating in time. This is controlled by a time slot structure, wheretwo time slots of 0.5 ms length each constitute a 1 ms frame. Downlink(DL) frames 21 are used for communication from the base station to themobile terminals and Uplink frames 22 are used for communication fromthe mobile terminals to the base stations.

To provide good coverage, base stations are usually placed at elevatedpositions. As a result, there is often line-of sight propagation betweenbase stations. Uplink traffic in one base station can therefore beseverely interfered by downlink traffic of an adjacent base station. Inorder to avoid this interference problem, all base stations within anetwork are timed synchronized. This means that under normal operatingconditions all base stations transmit only during the downlink frames 21and receive signals only during the uplink frames 22, where the downlinkframes 21 occur simultaneously across the full network and where theuplink frames 22 occur simultaneously across the full network. This iscalled TDD time synchronization and is illustrated in FIG. 2.

As described in the background, sleeping cells, as that term is used inthis description, is a faulty cell that has not generated an alarm or inany other way indicated a problem but still is not capable of carryingtraffic. The impact of a sleeping cell is that mobile terminals in thecorresponding coverage area cannot be served as the service disappearsin a sleeping cell.

With reference to FIGS. 3 and 4, embodiments of the invention monitoringthe performance of a sleeping cell candidate will now be described.

FIG. 3 is a schematic flow diagram that illustrates an example,non-limiting procedures for monitoring the performance of a base stationassociated with a sleeping cell candidate. A sleeping cell candidate isa cell that normally carries traffic volume but when the traffic volumeis seen to be zero for some time, the cell is suspected by themonitoring module to be faulty. This information is mediated to themonitoring module either directly from the base station itself or by theOMC that in turn monitors the traffic flows through the base stations,or by any other node that maintain information about the traffic volumesthat flow through the individual base stations.

A neighboring base station either receives a request for monitoring theperformance of a candidate base station from the monitoring module orautomatically initiates monitoring the performance of a candidate basestation. The candidate base station is a base station associated with asleeping cell candidate. The neighboring base station is a base stationwithin radio distance of the candidate base station, i.e. theneighboring base station and the candidate base station are located insuch a way that a radio communication signal from the candidate basestation can be detected and decoded at the position of the neighboringbase station and vice versa.

The neighboring base station communicates with the candidate basestation over the radio interface step S1 to set up a radio communicationchannel. When communicating with the candidate base station, theneighboring base station emulates a mobile terminal by following theprotocols and procedures defined for such mobile terminal in the LTEsystem, and appears as a mobile terminal that uses the offeredcommunication service of the candidate base station. In particular thismeans that the neighboring base station when emulating a mobile uses thefrequencies and time slots as is required by the mobile station. In aLTE FDD system this means, among others, that the base station in itscommunication with the candidate base station uses the uplink frequencyband for transmission and the downlink frequency band for reception ofradio signals. In the LTE TDD system this means, among others, that thethat the base station in its communication with the candidate basestation uses the uplink frames for transmission and the downlink framesfor reception of radio signals as illustrated in FIG. 6. The establishedradio communication channel is used in a first step to make an initialaccess, to register to the network and to establish a radio bearer foruser data in the same manner as a mobile terminal accesses the candidatebase station.

However if step S1 fails, possibly after a predetermined number ofattempts, i.e. the radio communication channel setting up fails, theneighboring base station determines that mobiles are not able to set upradio connections to the candidate base station, i.e. the candidate basestation is indeed a sleeping cell step S2. Subsequently the neighboringbase station informs the monitoring module and possibly the OMC via themonitoring module about the status of the candidate cell step S3. Theneighboring base station deregisters from the system, leaves theterminal emulation mode and resumes normal operation.

FIG. 4 is a schematic flow diagram according to one aspect of thepresent invention. A neighboring base station either receives a requestfor monitoring the performance of a candidate base station from themonitoring module or automatically initiates monitoring the performanceof a candidate base station. The candidate base station is a basestation associated with a sleeping cell candidate. The neighboring basestation is a base station within radio distance of the candidate basestation, i.e. the neighboring base station and the candidate basestation are located in such a way that a radio communication signal fromthe candidate base station can be detected and decoded at the positionof the neighboring base station and vice versa.

The neighboring base station communicates with the candidate basestation over the radio interface step S1 to set up a radio communicationchannel. When communicating with the candidate base station, theneighboring base station emulates a mobile terminal by following theprotocols and procedures defined for such mobile terminal in the LTEsystem, and appears as a mobile terminal that uses the offeredcommunication service of the candidate base station. In particular thismeans that the neighboring base station when emulating a mobile uses thefrequencies and time slots as is required by the mobile station. In aLTE FDD system this means, among others, that the base station in itscommunication with the candidate base station uses the uplink frequencyband for transmission and the downlink frequency band for reception ofradio signals. In the LTE TDD system this means, among others, that thebase station in its communication with the candidate base station usesthe uplink frames for transmission and the downlink frames for receptionof radio signals as illustrated in FIG. 6. The established radiocommunication channel is used in a first step to make an initial access,to register to the network and to establish a radio bearer for user datain the same manner as a mobile terminal accesses the candidate basestation. However if step S1 fails, possibly after a predetermined numberof attempts, i.e. the radio communication channel setting up fails, theneighboring base station determines that mobiles are not able to set upradio connections to the candidate base station, i.e. the candidate basestation is indeed a sleeping cell step S2. Subsequently the neighboringbase station informs the monitoring module and possibly the OMC via themonitoring module about the status of the candidate cell step S3. Theneighboring base station deregisters from the system, leaves theterminal emulation mode and resumes normal operation.

If the step S1 is successful, i.e. the radio communication channel issuccessfully established, the neighboring base station uses the radiocommunication channel to communicate with a content server through thecandidate base station step S4. The communication through the candidatebase station is here chosen to be the upload of one data file from theneighboring base station to the content server and the download of ananother file from the content server through the candidate base stationto the neighboring base station. However, the form of communication canbe any kind of communication that is offered by the system under normaloperation.

In step S5, The neighboring base station records and evaluates theresult of the communication. The record can include for example whetheror not a downloaded file was received within a predetermined timeframe,the download time, the value of the Bit Error Rate (BER), the packetloss rate and more. Based on the communication result the neighboringcell can determine whether the candidate base station is operating ornot. Specifically, in the case of a failed communication the neighboringbase station can conclude that the candidate base station does notsupport the communication service which indicates a faulty cell. Notethat the fault in this case can be located anywhere in the communicationchain between the radio interface and the content server, e.g. in theradio base station, in the transmission path “S1” or in the MME/SAE-GW.

The information about the operational state of the candidate basestation is then transmitted from the neighboring base station to themonitoring module for further handling step S6, possibly includingalarming the operator if the candidate base station is not operatingaccording to expectations.

In addition to the evaluation done locally in the neighboring basestation (as described above) the neighboring base station can transmitthe record itself to a central point in the network. This central pointcan be the monitoring module, the O&M center or any other node capableof receiving and evaluating the records from a set of base stations.Based on records transmitted from a multitude of neighboring basestations the central node can make conclusions about where in thecommunication chain a potential fault is most likely to be. If e.g. onlythe communication from a single base station has failed it is likelythat the fault is in the base station, or at least in equipment that isnot used in the communication path from other base station. If therecords indicate that the communication with the content server hasfailed through a large set of base station the fault is most likely in anode or equipment that is common for the communication paths from allthe failing base stations, e.g. a SAE GW or a common transmissionnetwork.

After the evaluation and the transmission of records and/or evaluationresults to the monitoring center the neighboring base stationderegisters from the system, leaves the terminal emulation mode andresumes normal operation step S7.

FIG. 5 is a function block diagram of a non-limiting example of a basestation 14 adapted to monitor a candidate base station in accordance,for example, with the procedures described above. The base station 14includes a controller 51, a wired circuit 57 having a S1 connectioninterface 52, and a radio circuit 58 having a radio transceiver 52coupled to an antenna interface 56. The controller 51 handles the dataprocessing of monitoring operations associated with the receivedmonitoring request and could be configured to automatically executemonitoring operations after a certain time period or in response to apredefined traffic condition. The S1 connection interface is adapted toreceive and transmit information on the S1 connection. The radiotransceiver 52 performs the baseband processing, filtering, frequencytranslation, amplification, and other operations necessary for radiocommunication.

The controller 51 includes several control entities, two of which shownin FIG. 4: a monitoring control 54 and an emulating control 55.

The monitoring control 54 receives and transmits monitoring-relatedmessages such as monitoring requests and reports and also performsmonitoring operations such as fault detection process. The receivedmonitoring request may include as an example the identity of thecandidate base station and mobile terminal related information to beused by the emulating control in the radio communication channel settingup process. The mobile terminal related information may include the sameinformation stored in a Subscriber Identity Module (SIM) card such asthe International Mobile Subscriber Identifier (IMSI). In anotherembodiment mobile terminal related information is not included in themonitoring request but is preconfigured in the base station and could beretrieved by the emulating control 55 when needed.

The emulating control 55 is used to change the mode of the base stationto a terminal emulation mode and to follow the protocols and proceduredefined for mobile terminals in the LTE TDD system. When changing themode of the base station to a terminal emulating mode, the emulatingcontrol 55 sets up a radio communication channel with a candidate basestation by making an initial access, registering to the network andestablishing a radio bearer for user data. In one embodiment theemulating control 55 cancels the normal operation of the base station 14when starting the emulation process and schedules the emulation processto occur in periods of low traffic in the base station 14, i.e. othermobile terminals will not be able to use the services offered by thebase station 14 in the terminal emulation mode. In another embodiment,the emulating control 55 uses a fraction of the spectrum of the basestation 14 for the terminal emulation mode, while the remaining fractionof spectrum is used for normal operation of the base station 14, i.e.mobile terminals will be able to use a fraction of the offered capacityof the base station 14.

FIG. 6 illustrates a protocol for transmission illustrating uplink anddownlink communication in time domain according to one aspect of theinvention. As explained in FIG. 2, in the TDD mode of LTE, an unpairedfrequency band is defined from which both the uplink and downlinkchannels are selected. A TDD transceiver can therefore not transmit andreceive simultaneously. The uplink communication and downlinkcommunication in the TDD system is alternating in time as explained.

Downlink (DL) frames 61 are used for communication from the base stationto the mobile terminals and Uplink frames 62 are used for communicationfrom the mobile terminals to the base stations. After receiving amonitoring request at base station (BS B) 63 to monitor a sleeping cellcandidate in this case base station (BS A) 64, the BS B 63 emulates amobile terminal and appears as a mobile terminal to the candidate basestation (BS A) 64. To be able to emulate a mobile terminal, the BS B 63use the downlink time frame 61 for reception and the uplink time frame62 for transmission as illustrates in FIG. 5.

FIG. 7 illustrates a signaling diagram according to one embodiment ofthe invention. The monitoring module 12 sends a monitoring request 71 toneighboring BS 63. When the monitoring request 71 is received, theneighboring BS 63 communicates with the candidate BS 64 over the radiointerface to set up a radio communication channel. In another embodimentof the invention, not illustrated in FIG. 7, the neighboring BS 63automatically communicates with the candidate BS 64 over the radiointerface to set up a radio communication channel without receiving themonitoring request. When communicating with the candidate BS 64, theneighboring BS 63 emulates a mobile terminal by sending an accessrequest 72 to the candidate BS 64 and then the neighboring BS 63 sendregistration information 73 to the candidate BS 64. Upon receiving theregistration information the candidate BS 64 establishes a radio bearer74 for user data. The neighboring BS 63 monitors the establishment ofthe radio communication channel and if one the above described signalingfails, i.e. one of the signaling 72, 73 or 74 fails, the neighboring BS63 transmits monitoring information 75 indicating the failure to themonitoring module 12 and the neighboring BS 63 performs deregistration76 from the network and resumes normal operation.

FIG. 8 illustrates a signaling diagram according to another embodimentof the invention. Comparing to FIG. 7, the signaling 71, 72, 73 and 74are the same, i.e. receiving a monitoring request and establishing aradio communication channel is performed in the same way, but in thiscase the neighboring BS 63 successfully establishes a radiocommunication channel with the candidate BS 64. When the radiocommunication channel is successfully established the neighboring BS 63uploads 81 first data file 81 to the content server 19 through thecandidate BS 64. The Content server 19 downloads 82 a second data fileto the neighboring BS 63 through the candidate BS 64. The neighboring BS63 monitors the communication with the content server 19 and transmits83 monitoring information to the monitoring module 12 indicating thefailure or the success of the data file transfers. The monitoringinformation is sent to a central point (CP) in the network. This centralpoint can be the monitoring module 12, the O&M center 13 or any othernode capable of receiving and evaluating the monitoring information.When the monitoring information is sent, the neighboring BS 63deregisters 84 from the network and resumes normal operation.

The present invention may be embodied in many different forms and shouldnot be construed as limited to the embodiments set forth herein; rather,these embodiments are provided so that this disclosure will be thoroughand complete, and will fully support the enclosed set of claims.

1-21. (canceled)
 22. A method for monitoring the performance of at leasta second base station among a plurality of base stations in a cellularcommunications system, said method comprising: setting up a radiocommunication channel for communication between a first base station andthe second base station; monitoring by the first base station thecommunication between the first and second base stations; initiating bythe first base station a connection being set up between the first basestation and a content server, through the second base station; andmonitoring by the first base station the connection between the firstbase station and the content server.
 23. The method of claim 22, whereinsaid step of setting up the radio communication channel is performed inresponse to a monitoring request generated by a monitoring module formonitoring the performance of said second base station.
 24. The methodof claim 23, wherein said step of setting up the radio communicationchannel is performed in response to a monitoring request generated by amonitoring module, and wherein the monitoring module is incorporatedwithin the first base station.
 25. The method as claimed in claim 23,wherein said step of setting up the radio communication channel isperformed in response to a received monitoring request transmitted froma monitoring module.
 26. The method of claim 23, further comprising thesteps of: monitoring the setting up of the radio communication channel;and transmitting monitoring information in response to the failure ofsetting up the radio communication channel.
 27. The method of claim 22,wherein said step of setting up the radio communication channelcomprises emulating a mobile terminal.
 28. The method of claim 27,wherein said step of setting up the radio communication channelcomprises: registering the emulated mobile terminal at said second basestation; and establishing a radio bearer for user data.
 29. The methodof claim 22, further comprising transmitting monitoring information inresponse to a predetermined condition being fulfilled.
 30. The method ofclaim 29, further comprising the steps of: uploading from the first basestation a first file to the content server; and downloading from thecontent server a second file to the first base station.
 31. The methodof claim 30, wherein the predetermined condition indicates the successor failure of the file transfers.
 32. A first base station formonitoring the performance of a second base station in a radiocommunication system, wherein said base station comprises: a radiotransceiver; a controller, coupled to said transceiver, and adapted toinitiate a procedure for setting up a radio communication channel withthe second base station using said radio transceiver in response to amonitoring request, wherein said controller is further adapted to:monitor the setting up procedure; initiate a connection with a contentserver being set up through the second base station; and monitor theconnection between said first base station and the content server. 33.The first base station of claim 32, wherein the monitoring request formonitoring the performance of said second base station is generated by amonitoring module.
 34. The first base station of claim 33, wherein themonitoring module is incorporated within said first base station. 35.The first base station of claim 33, wherein the controller is furtheradapted to transmit monitoring information to the monitoring modulecenter in response to a faulty condition during the setting up of theradio communication channel.
 36. The first base station of claim 32,wherein the monitoring request for monitoring the performance of saidsecond base station is transmitted from a monitoring module.
 37. Thefirst base station of claim 32, wherein the controller is furtheradapted to emulate a mobile terminal in the setting up of the radiocommunication channel.
 38. The first base station of claim 37, whereinthe radio transceiver is adapted to transmit on an uplink channelintended for transmitting information from a mobile terminal to a basestation, and to receive on a downlink channel intended for transmittinginformation from a base station to a mobile terminal.
 39. The first basestation of claim 38, wherein the controller is adapted to access thesecond base station, register the emulated mobile terminal and establisha radio bearer for user data in the same way as a mobile terminal setsup a radio communication channel with the second base station.
 40. Thefirst base station of claim 32, wherein the controller is furtheradapted to upload a first file to the content server and to download asecond file to said first base station.
 41. The first base station ofclaim 40, wherein the controller is further adapted to transmitmonitoring information in response to a predetermined condition in theconnection between said first base station and the content server. 42.The first base station of claim 41, wherein the predetermined conditionindicates the success or failure of the file transfers.